1. Field of the Invention
This invention relates to a method and apparatus for providing alphanumeric input to computers and other electronic devices by means of operating four keys (or other four sensors) by four fingers of one hand. The device can be extremely portable and easily operated by one hand, especially since the thumb is not used for operating the keys.
The major fields of use for this invention include:                As a fully functional alphanumeric keyboard for portable computers, Personal Digital Assistants (PDAs), cellular phones, pagers and any other portable electronic devices. Since the invention requires only four buttons/keys to operate, it can easily be incorporated in even the smallest devices.        The four keys required by the invention can be replaced with four sensors attached to the four fingers by rings or otherwise (or even implanted . . . ). The sensors would detect small movements of each finger, change of tension in the muscles or even the bio-electrical signals of the nerves controlling each finger. The movements (or the ‘intentions’ to move) of the four fingers would then be decoded the same way as for the four key keyboard.        As an input device for desktop computers or any other ‘stationary’ electronic devices—as a replacement or in addition to the conventional keyboard. The biggest advantage of using a one-hand keyboard being the freedom of the other hand for other chores.        The invention can also be combined with other input devices, like the mouse: a device with the standard mouse buttons and the four buttons/keys required by this invention would provide total mouse pointer control combined with full alphanumeric input—and still be operated just by one hand.        As a fully functional alphanumeric keyboard for handicapped people who can only use one hand.        
2. Description of the Prior Art
A number of attempts to design a keyboard operated by one hand have been described in the prior art. These include inventions covered by the following U.S. patents: U.S. Pat. Nos. 4,042,777; 4,344,069; 4,360,892; 4,381,502; 4,555,193; 4,836,700; 4,988,997; 5,288,158.
The problems with these keyboard designs can be divided into two major groups, at least one of them is significant for each of the above inventions:                Too many keys—usually an array of at least 3 by 4 keys, movements of fingers from key to key as well as the chord combinations for all the characters have to be memorized. The number of keys also makes the keyboards too large for truly portable devices.        The keyboards use chords, which for a significant portion of even the basic alphabet characters require pressing three or four fingers/digits (up-to all five digits of one hand), making them very hard to remember and use.        
Also, the thumb is used to operate at least one key, making it hard to comfortably hold/operate a portable device that incorporates the keyboard.